In recent years, a semiconductor device has been formed so as to have a fine structure and a stacked structure. As the structure of the semiconductor device becomes fine, overlay accuracy to be required has become high. Further, since distortion is generated in the plane of a wafer due to an influence of film stress caused by stacking, it is difficult to ensure overlay accuracy.
A correction method, which calculates correction values of exposure positions on the basis of results of overlay measurement and feeds the correction values back to an exposure apparatus, is known as a correction method for ensuring overlay accuracy. Further, there is also known a correction method, which calculates an X-direction shape change displacement and a Y-direction shape change displacement from a difference between the measurement results of wafers of lower and upper layers previously measured, calculates correction values of exposure positions on the basis of the X-direction shape change displacement and the Y-direction shape change displacement, and feeds the correction values back to an exposure apparatus.
In a correction method that feeds correction value back to an exposure apparatus, calibration using the results of overlay measurement on results of wafer shape measurement is necessary to improve the correction accuracy. However, when differences are generated between the shapes of wafers to be corrected, overlay measurement of a plurality of wafers needs to be performed. For this reason, load is applied to an overlay measurement apparatus. Further, since calibration using the results of overlay measurement is needed, cycle time, which is required until the calculation of a feedforward correction value, is lengthened. As a result, time is required until a calibrated correction value is reflected.